Optical rotary junction incorporating a hollow shaft DC motor for high-speed catheter-based optical coherence tomography

In intravascular optical coherence tomography (OCT), the optical rotary junction plays an important role in rotating and pulling back the catheter to generate cross-sectional coronary artery images. To meet the requirements of high-speed intravascular OCT in a clinical setting, the rotary junction should generate high torque and low vibration. In this Letter, we demonstrate an ultrahigh speed optical rotary junction incorporating a hollow shaft brushless DC servomotor to remove a pulley belt, or a gear to minimize vibration noise and transfer stable torque. To evaluate the performance of the rotary junction, the vibration noise and variation of rotation were measured as a function of motor speed. The results showed that the rotary junction rotated the catheter at 42,000 revolutions per minute, with an optical transmission loss of 1.2 dB. To assess the feasibility of the rotary junction for high-speed catheter-based OCT, OCT imaging of the cylindrical shape of a phantom made by two overlapped plastic straws was performed at a rate of 200 frames/s.